Many portable electronic devices include displays for displaying various types of images. Examples of such displays include electrowetting displays (EWDs), liquid crystal displays (LCDs), electrophoretic displays (EPDs), light emitting diode displays (LED displays), etc. In EWD applications, two substrates or support plates are coupled together wholly or partially under or in contact with electrowetting fluids using an adhesive or other sealing material. After positioning a top substrate and filling the substrates with electrowetting fluids, the top substrate needs to be attached to a bottom substrate. A sealing material such as, for example, ultraviolet (UV) curable epoxy glue, is used for attaching the top and bottom substrates to one another. The uncured glue is dispensed in a desired pattern on the top substrate before the substrates filling process commences, wherein the glue can be dispensed in globular deposits or as a substantially continuous pattern of glue on the periphery of the top substrate before filling with electrowetting fluids and coupling the two substrates into a EWD device. During filling and coupling, the uncured glue is predominantly in contact with a second fluid of the two fluids. When the uncured glue comes into contact or is immersed in the second fluid, an undesirable fluid-flow phenomenon occurs that renders the application of the glue cumbersome, for example, when the glue is under the second fluid. This phenomenon can be explained with respect to FIG. 1, which is a cross-sectional view of a line of uncured glue on a substrate.
When a line of uncured ultraviolet (UV) curable epoxy glue 100 is immersed in a second fluid 102, which, for example, may be electrically conductive or polar, and may be water or a salt solution such as a solution of potassium chloride in a mixture of water and ethyl alcohol, the dispensed UV curable epoxy glue 100 may be pushed back, adversely displaced or dismounted from the substrate by the force of the second fluid (represented as Ffluid in FIG. 1). The polarity of the second fluid 102 matches better with the polarity of a conducting layer of material such as an indium tin oxide (ITO) layer 104 (e.g., an ITO layer 104 on a substrate 106) in comparison to the polarity of the UV curable epoxy glue 100, since both the second fluid 102 and the ITO 104 are hydrophilic while the UV curable epoxy glue 100 is more hydrophobic. The second fluid 102 begins to compete with the UV curable epoxy glue 100 to wet the ITO surface 104. Because of this competition the contact diameter (d) of the UV curable epoxy glue 100 with the ITO surface 104 decreases (dair>dfluid), where dair represents the contact diameter of the UV curable epoxy glue 100 with the ITO surface 104 in air upon being initially dispensed and dfluid represents the contact diameter of the UV curable epoxy glue 100 with the ITO surface 104 in the second fluid 102. A decrease in contact diameter is a problem because it leads to a decrease in adhesion of the top and bottom substrates.
Accordingly, the behavior of the UV curable epoxy glue 100 under the fluid 102 results in drawbacks in manufacturing of EWD display devices. For example, extra time and space may be needed in the manufacturing line.